Incidence of chromosome abnormalities in the Sultanate of Oman

To evaluate the cytogenetic findings in Omani children referred for suspected chromosomal anomalies that caused a variety of clinical disorders. Secondly, to study the frequency of chromosomal abnormalities in these patients and to compare our results with those reported elsewhere.

We performed chromosomal analysis on 1800 consecutive pediatric patients referred to the Cytogenetics section between June 1999 and May 2004 at Central Public Health Laboratories, Sultanate of Oman. Indication for referrals for exclusion of chromosomal rearrangements was multiple congenital anomalies, dysmorphic features, unclassified mental retardation, developmental delay, growth, and endocrine disorders. We carried out the lymphocyte culture according to standard methods.

We found various types of chromosomal anomalies in 510 (28.3%) children and showed abnormal karyotypes in the form of trisomy 21 (391; 21.7%), trisomy 18 (32; 1.8%), trisomy 13 (20; 1.1%), sex chromosome aberrations (50; 2.8%) and other types of abnormalities (17; 0.95%). There was a considerable phenotypic-cytogenetic heterogeneity. We found a high rate of chromosomal abnormalities in the present study, and we observed variations in the frequency of chromosomal aberrations reported by different investigators.

The higher incidence of the chromosomal abnormalities demonstrates the importance of cytogenetic evaluation in patients with dysmorphic features and congenital anomalies. Our findings suggest that chromosome analysis is a useful tool in the investigation of children with genetic disorders of unknown origin for confirmation of clinical diagnosis and proper medical care followed by genetic counseling and management.